Considerable data exist which characterize the human IgG antibody response to human immunodeficiency virus (HIV). In contrast, the presence and precise nature of the IgM response is largely unknown. As for previously described viral immunities, the IgM response may indicate acute exposure and/or infection and thus be an early event in the pathogenesis of the disease. The long term goal of this application is to provide standardized technology for measurements of IgM anti-HIV immunity. The specific aims of the present work are to investigate those parameters associated with the construction of sensitive and precise immunoassays for IgM detection. Murine monoclonal antibodies to HIV subcomponents will be used as probes to precisely define the specificity of the IgM response; these include core proteins, envelope glycoproteins and reverse transcriptase. The pre-clinical utility of IgM anti-HIV monitoring will be investigating versus a panel of sera obtained from individuals at high risk and from those with various Walter-Reed stages of HIV infection. Horizontal specimens obtained prior to and during active seroconversion will be studied in order to define the temporal characteristics of the IgM response. All results will be compared to those data acquired from the use of IgG antibody assays on the same specimens.